GWT Uncaught exception escaped - gwt

Question

I have created a new google application using GWT, and it runs fine. But when i click a button that is responsible for performing some action with the server side, it throws an unusual error. Please could someone offer some help? Thank you in advance :(
Here is the code:
package com.ukstudentfeedback.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.DialogBox;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.ukstudentfeedback.shared.FieldVerifier;
import com.ukstudentfeedback.client.MailClient;
import com.ukstudentfeedback.client.MailClientAsync;
public class Ukstudentfeedback implements EntryPoint{
private static final String SERVER_ERROR = "An error occurred while "
+ "attempting to contact the server. Please check your network "
+ "connection and try again.";
/**
* Create a remote service proxy to talk to the server-side Greeting service.
*/
private final MailClientAsync sendMessage = GWT
.create(MailClient.class);
// ...
public void onModuleLoad()
{
java.lang.System.out.println("I finally worked!");
final Button sendButton;
final TextBox toField, fromField, subjectField, messageField;
final Label errorLabel = new Label();
sendButton = new Button("Send");
toField = new TextBox();
fromField = new TextBox();
subjectField = new TextBox();
messageField = new TextBox();
sendButton.addStyleName("sendButton");
toField.setText("Testing");
// Add the nameField and sendButton to the RootPanel
// Use RootPanel.get() to get the entire body element
RootPanel.get("sendButton").add(sendButton);
RootPanel.get("To").add(toField);
RootPanel.get("From").add(fromField);
RootPanel.get("Subject").add(subjectField);
RootPanel.get("Message").add(messageField);
RootPanel.get("errorLabelContainer").add(errorLabel);
// Focus the cursor on the to field when the app loads
toField.setFocus(true);
toField.selectAll();
//sendButton.setEnabled(true);
// Create the popup dialog box
final DialogBox dialogBox = new DialogBox();
dialogBox.setText("Message Sent");
dialogBox.setAnimationEnabled(true);
final Button closeButton = new Button("Close");
// We can set the id of a widget by accessing its Element
closeButton.getElement().setId("closeButton");
final Label textToServerLabel = new Label();
final HTML serverResponseLabel = new HTML();
VerticalPanel dialogVPanel = new VerticalPanel();
dialogVPanel.addStyleName("dialogVPanel");
dialogVPanel.add(new HTML("<b>Message Sent:</b>"));
dialogVPanel.add(textToServerLabel);
dialogVPanel.add(new HTML("<br><b>Server replies:</b>"));
dialogVPanel.add(serverResponseLabel);
dialogVPanel.setHorizontalAlignment(VerticalPanel.ALIGN_RIGHT);
dialogVPanel.add(closeButton);
dialogBox.setWidget(dialogVPanel);
// Add a handler to close the DialogBox
closeButton.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event) {
dialogBox.hide();
sendButton.setEnabled(true);
sendButton.setFocus(true);
}
});
// Create a handler for the sendButton and nameField
class MyHandler implements ClickHandler{
/**
* Fired when the user clicks on the sendButton.
*/
public void onClick(ClickEvent event) {
java.lang.System.out.println("I have been clicked");
sendMessageToServer();
}
public void sendMessageToServer()
{
errorLabel.setText("");
String to = toField.getText();
String from = fromField.getText();
String subject = subjectField.getText();
String message = messageField.getText();
if (!FieldVerifier.isValidName(to, from, subject, message)) {
errorLabel.setText("Please enter at least four characters");
return;
}
sendButton.setEnabled(false);
textToServerLabel.setText("Hello");
serverResponseLabel.setText("");
sendMessage.sendMessage(to, from, subject, message, new AsyncCallback<String>() {
public void onFailure(Throwable caught) {
// Show the RPC error message to the user
dialogBox
.setText("Message sending Failed");
serverResponseLabel
.addStyleName("serverResponseLabelError");
serverResponseLabel.setHTML(SERVER_ERROR);
dialogBox.center();
closeButton.setFocus(true);
}
public void onSuccess(String result) {
dialogBox.setText("Message Sent");
serverResponseLabel
.removeStyleName("serverResponseLabelError");
serverResponseLabel.setHTML(result);
dialogBox.center();
closeButton.setFocus(true);
}
});
}
}
// Add a handler to send the name to the server
MyHandler handler = new MyHandler();
sendButton.addClickHandler(handler);
}
}
Server side:
package com.ukstudentfeedback.server;
import java.io.UnsupportedEncodingException;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import com.ukstudentfeedback.shared.FieldVerifier;
#SuppressWarnings("serial")
public class MailServerImpl extends RemoteServiceServlet{
public void sendMessage(String to, String from, String subject, String message) throws IllegalArgumentException
{
// Verify that no input is null.
if (!FieldVerifier.isValidName(to, from, subject, message)) {
// If the input is not valid, throw an IllegalArgumentException back to
// the client.
throw new IllegalArgumentException(
"Name must be at least 4 characters long");
}
Properties props = new Properties();
Session session = Session.getDefaultInstance(props, null);
try
{
Message msg = new MimeMessage(session);
msg.setFrom(new InternetAddress(from, "Admin"));
msg.addRecipient(Message.RecipientType.TO,
new InternetAddress(to, "Mr. User"));
msg.setSubject(subject);
msg.setText(message);
Transport.send(msg);
}
catch (AddressException e)
{
// ...
e.printStackTrace();
} catch (MessagingException e)
{
// ...
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Error Stack:
23:26:55.817 [ERROR] [ukstudentfeedback] Uncaught exception escaped
com.google.gwt.event.shared.UmbrellaException: One or more exceptions caught, see full set in UmbrellaException#getCauses
at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:129)
at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:129)
at com.google.gwt.event.dom.client.DomEvent.fireNativeEvent(DomEvent.java:116)
at com.google.gwt.user.client.ui.Widget.onBrowserEvent(Widget.java:177)
at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1351)
at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1307)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
at sun.reflect.GeneratedMethodAccessor27.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292)
at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546)
at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363)
at java.lang.Thread.run(Thread.java:680)
Caused by: com.google.gwt.user.client.rpc.ServiceDefTarget$NoServiceEntryPointSpecifiedException: Service implementation URL not specified
at com.google.gwt.user.client.rpc.impl.RemoteServiceProxy.doPrepareRequestBuilderImpl(RemoteServiceProxy.java:430)
at com.google.gwt.user.client.rpc.impl.RemoteServiceProxy.doInvoke(RemoteServiceProxy.java:368)
at com.google.gwt.user.client.rpc.impl.RemoteServiceProxy$ServiceHelper.finish(RemoteServiceProxy.java:74)
at com.ukstudentfeedback.client.MailClient_Proxy.sendMessage(MailClient_Proxy.java:38)
at com.ukstudentfeedback.client.Ukstudentfeedback$1MyHandler.sendMessageToServer(Ukstudentfeedback.java:118)
at com.ukstudentfeedback.client.Ukstudentfeedback$1MyHandler.onClick(Ukstudentfeedback.java:98)
at com.google.gwt.event.dom.client.ClickEvent.dispatch(ClickEvent.java:54)
at com.google.gwt.event.dom.client.ClickEvent.dispatch(ClickEvent.java:1)
at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:1)
at com.google.web.bindery.event.shared.EventBus.dispatchEvent(EventBus.java:40)
at com.google.web.bindery.event.shared.SimpleEventBus.doFire(SimpleEventBus.java:193)
at com.google.web.bindery.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:88)
at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:127)
at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:129)
at com.google.gwt.event.dom.client.DomEvent.fireNativeEvent(DomEvent.java:116)
at com.google.gwt.user.client.ui.Widget.onBrowserEvent(Widget.java:177)
at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1351)
at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1307)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
at sun.reflect.GeneratedMethodAccessor27.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292)
at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546)
at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363)
at java.lang.Thread.run(Thread.java:680)

Answer 1

To find the cause of an UmbrellaException look for "Caused by":
Caused by:
com.google.gwt.user.client.rpc.ServiceDefTarget$NoServiceEntryPointSpecifiedException:
Service implementation URL not specified
Specify the remote service URL by doing either of the following:
Adding a RemoteServiceRelativePath annotation to your MailClientAsync interface.
Calling ServiceDefTarget#setServiceEntryPoint:
((ServiceDefTarget)sendMessage).
setServiceEntryPoint("http://www.example.com/service");